I have a 1998 Blazer Lt, 4 door, 4wd. It. It has 126k miles. I have replaced the fuel filter. I had my mechanic check the spark plugs and air filter. They look fairly new. He didn’t notice any leaks. I am getting around 10 mpg. What should I do next? Replace the pcv valve? Clean the maf sensor?

 

I would hook up a scanner and check what the O2 sensors are reading while you're driving. Also check the fuel trims to see if you're running rich. Does it seem to run well, other than the mileage? Did it used to be better, and just suddenly got bad?

 

It seems to run well. It runs quiet. It idles around 600 rpm.

 

So, is the bad gas mileage a new thing, or has it always been that way?

 

I have only had the truck for 3 months and I have driven it less than 400 miles. It has had the low mpg since I got it.

 

I have a 1998 Jimmy 1998 Lt, 4 door, 4wd with 160,000 miles. It gets about 11 mpg in winter and 14 in summer (all city). To me this seems a little low, but it was even worse when I bought the vehicle a year ago.

I replaced the fan clutch, fuel filter, air filter, PCV valve, and cleaned the MAF sensor and the EGR valve. This possibly bumped up the mileage by maybe 1 or 2 mpg.

This afternoon I'm going to change the thermostat. The vehicle has a 160 thermostat instead of the OEM 195 thermostat, and the vehicle is running cool. We'll see if this helps.

Also, this summer the plugs, wires and rotor will get replaced.

 

Stovey, does yours have a 160 thermostat or is that what you are going to put in it?

 

I installed the 160 thermostat last winter by mistake, and replaced it this afternoon with the correct 195 thermostat.

 

Change out your O2 sensors. They are a maintenance item that need to be changed out and will affect your mileage. I'm guessing they have never been changed out ever as most people know they have them but don't realize they need to be changed out. I change mine out every 100K, and I'm about due for another set.

 

If changing the sensors gets you 3 mpg you will save 3 gallons a month.